Configuration Guide User guide

1416 FastIron Configuration Guide
53-1002494-02
Route flap dampening configuration
The <suppress> parameter specifies how high a route penalty can become before the Layer 3
switch suppresses the route. You can set the suppression threshold to a value from 1 through
20000. The default is 2000 (two “flaps”).
The <max-suppress-time> parameter specifies the maximum number of minutes that a route can
be suppressed regardless of how unstable it is. You can set the maximum suppression time to a
value from 1 through 20000 minutes. The default is four times the half-life setting. Thus, if you use
the default half-life of 15 minutes, the maximum suppression time is 60 minutes.
The following example shows how to change the dampening parameters.
Brocade(config-bgp-router)#dampening 20 200 2500 40
This command changes the half-life to 20 minutes, the reuse threshold to 200, the suppression
threshold to 2500, and the maximum number of minutes a route can be dampened to 40.
NOTE
To change any of the parameters, you must specify all the parameters with the command. If you want
to leave some parameters unchanged, enter their default values.
Using a route map to configure route flap dampening
for specific routes
Route maps enable you to fine tune route flap dampening parameters for individual routes. To
configure route flap dampening parameters using route maps, configure BGP4 address filters for
each route you want to set the dampening parameters for, then configure route map entries that
set the dampening parameters for those routes. The following sections show examples.
To configure address filters and a route map for dampening specific routes, enter commands such
as the following.
The address-filter commands in this example configure two BGP4 address filters, for networks
209.157.22.0 and 209.157.23.0. The first route-map command creates an entry in a route map
called “DAMPENING_MAP”. Within this entry of the route map, the match command matches
based on address filter 9, and the set command sets the dampening parameters for the route that
matches. Thus, for BGP4 routes to 209.157.22.0, the Layer 3 switch uses the route map to set the
dampening parameters. These parameters override the globally configured dampening
parameters.
Brocade(config)#router bgp
Brocade(config-bgp-router)#address-filter 9 permit 209.157.22.0 255.255.255.0
255.255.255.0 255.255.255.0
Brocade(config-bgp-router)#address-filter 10 permit 209.157.23.0 255.255.255.0
255.255.255.0 255.255.255.0
Brocade(config-bgp-router)#exit
Brocade(config)#route-map DAMPENING_MAP permit 9
Brocade(config-routemap DAMPENING_MAP)#match address-filters 9
Brocade(config-routemap DAMPENING_MAP)#set dampening 10 200 2500 40
Brocade(config-routemap DAMPENING_MAP)#exit
Brocade(config)#route-map DAMPENING_MAP permit 10
Brocade(config-routemap DAMPENING_MAP)#match address-filters 10
Brocade(config-routemap DAMPENING_MAP)#set dampening 20 200 2500 60
Brocade(config-routemap DAMPENING_MAP)#router bgp
Brocade(config-bgp-router)#dampening route-map DAMPENING_MAP